Formation and variability of the Lofoten basin vortex in a high-resolution ocean model

Volkov, Denis; Kubryakov, A. A.; Lumpkin, Rick

doi:10.1016/j.dsr.2015.09.001

Cited by 60 publications

(72 citation statements)

References 40 publications

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“…Whereas most eddies are transient features, they found evidence that this eddy most likely is permanent and deep reaching. Both satellite observations (Raj et al, 2015) and ocean current modelling (Volkov et al, 2015) also confirm that variations are caused by mesoscale eddies. Yet, due to the challenges to accurately relate tracked schools with in situ current velocity in our study, all observed current variations along the skip track are presumably not caused by eddies.…”

Section: Current System and Mackerel Behaviourmentioning

confidence: 55%

Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

Nøttestad

Diaz

Peña

et al. 2015

ICES Journal of Marine Science

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High abundance of Northeast Atlantic mackerel (Scomber scombrus L.), combined with limited food resources, may now force mackerel to enter new and productive regions in the northern Norwegian Sea. However, it is not known how mackerel exploit the spatially varying feeding resources, and their vertical distribution and swimming behaviour are also largely unknown. During an ecosystem survey in the Norwegian Sea during the summer feeding season, swimming direction, and speed of mackerel schools were recorded with high-frequency omnidirectional sonar in four different regions relative to currents, ambient temperature, and zooplankton. A total of 251 schools were tracked, and fish and zooplankton were sampled with pelagic trawl and WP-2 plankton net. Except for the southwest region, swimming direction of the tracked schools coincided with the prevailing northerly Atlantic current direction in the Norwegian Sea. Swimming with the current saves energy, and the current also provides a directional cue towards the most productive areas in the northern Norwegian Sea. Average mean swimming speed in all regions combined was 3.8 body lengths s 21 . However, fish did not swim in a straight course, but often changed direction, suggesting active feeding in the near field. Fish were largest and swimming speed lowest in the northwest region which had the highest plankton concentrations and lowest temperature. Mackerel swam close to the surface at a depth of 8-39 m, with all schools staying above the thermocline in waters of at least 68C. In surface waters, mackerel encounter improved foraging rate and swimming performance. Going with the flow until temperature is too low, based on an expectation of increasing foraging rate towards the north while utilizing available prey under way, could be a simple and robust feeding strategy for mackerel in the Norwegian Sea.

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Section: Current System and Mackerel Behaviourmentioning

confidence: 55%

Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

Nøttestad

Diaz

Peña

et al. 2015

ICES Journal of Marine Science

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“…The sum of eddy observations identified in each altimeter map of every single eddy satisfying the above-mentioned criteria is given in Table 2. The Lofoten Basin is a region known for eddy mergers and eddy break-ups (Köhl 2007;Raj et al 2015;Volkov, Kubryakov, and Lumpkin 2015). The eddy-tracking algorithm employed in this study accounts for the eddy break-up process and mergers.…”

Section: Hybrid Eddy Detection Algorithmmentioning

confidence: 99%

“…One of the most extensively studied mesoscale features in the Lofoten Basin is the Lofoten Vortex Korablev 1995a, 1995b;Köhl 2007;Rossby, Prater, and Søiland 2009;Koszalka et al 2011;Søiland and Rossby 2013;Volkov, Belonenko, and Foux 2013;Volkov, Kubryakov, and Lumpkin 2015;Raj et al 2015). This energetic, quasi-permanent anticyclonic eddy resides in the deep western part of the Lofoten Basin and is sustained mainly due to the energy transfer from eddy mergers.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main data sets used in the detection of Lofoten Basin eddies is the weekly data (AVISO10) provided by AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic data; e.g. Volkov, Belonenko, and Foux 2013;Volkov, Kubryakov, and Lumpkin 2015;Raj et al 2015). Recently AVISO centre carried out a complete reprocessing of the SLA data set (AVISO14; Duacs/AVISO 2014) and a daily data set is provided, using which Capet et al (2014) found improvement in the detection of eddies in the tropics and subtropics.…”

Section: Introductionmentioning

confidence: 99%

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Monitoring the mesoscale eddies of the Lofoten Basin: importance, progress, and challenges

Raj¹,

Halo

2016

International Journal of Remote Sensing

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The Lofoten Basin is a 'hot spot' of intense mesoscale eddy activity in the Nordic Seas. The mesoscale eddies of the Lofoten Basin can be coupled to the heat transport, local climate, and fisheries of the region. During the past two decades, the European satellite missions European Remote Sensing (ERS) satellite and Environmental Satellite (ENVISAT) have played a major part in delivering continuous altimeter measurements over the Lofoten Basin. In recent years, automated eddy detection and tracking methods have revolutionized the long-term monitoring of eddies in the Lofoten Basin from the gridded altimeter data.

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“…The vortex has a doubly convex lens structure and is associated with deep penetration of Atlantic Water down to 1000 m depth [ Raj et al ., ]. It is understood to be sustained by receiving energy from other anticyclonic eddies in the Lofoten Basin via eddy merging [ Raj et al ., ; Volkov et al ., ]. Even though the Lofoten Vortex has been the focus of many studies, the eddy activity (number of eddies, eddy life, eddy genesis, eddy intensity, eddy drift) of the Lofoten Basin in general is less explored.…”

Section: Introductionmentioning

confidence: 99%

Quantifying mesoscale eddies in the Lofoten Basin

Raj¹,

Johannessen

Eldevik

et al. 2016

JGR Oceans

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The Lofoten Basin is the most eddy rich region in the Norwegian Sea. In this paper, the characteristics of these eddies are investigated from a comprehensive database of nearly two decades of satellite altimeter data (1995–2013) together with Argo profiling floats and surface drifter data. An automated method identified 1695/1666 individual anticyclonic/cyclonic eddies in the Lofoten Basin from more than 10,000 altimeter‐based eddy observations. The eddies are found to be predominantly generated and residing locally. The spatial distributions of lifetime, occurrence, generation sites, size, intensity, and drift of the eddies are studied in detail. The anticyclonic eddies in the Lofoten Basin are the most long‐lived eddies (>60 days), especially in the western part of the basin. We reveal two hotspots of eddy occurrence on either side of the Lofoten Basin. Furthermore, we infer a cyclonic drift of eddies in the western Lofoten Basin. Barotropic energy conversion rates reveals energy transfer from the slope current to the eddies during winter. An automated colocation of surface drifters trapped inside the altimeter‐based eddies are used to corroborate the orbital speed of the anticyclonic and cyclonic eddies. Moreover, the vertical structure of the altimeter‐based eddies is examined using colocated Argo profiling float profiles. Combination of altimetry, Argo floats, and surface drifter data is therefore considered to be a promising observation‐based approach for further studies of the role of eddies in transport of heat and biomass from the slope current to the Lofoten Basin.

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Formation and variability of the Lofoten basin vortex in a high-resolution ocean model

Cited by 60 publications

References 40 publications

Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

Feeding strategy of mackerel in the Norwegian Sea relative to currents, temperature, and prey

Monitoring the mesoscale eddies of the Lofoten Basin: importance, progress, and challenges

Quantifying mesoscale eddies in the Lofoten Basin

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